Analysts are predicting an unexpected headwind for the BSE, India's oldest stock exchange, in the form of so-called Graded Surveillance Measures (GSM) and compulsory delisting — both actions initiated by the market regulator Securities and Exchange Board of India. About 90 per cent of the 331 companies facing the heat of regulator and the government are exclusively listed on the BSE. They say, the revenue of the BSE could see some impact due to the move in the next two quarters. "There is a risk of additional impact in future coming from potential delisting of stocks, which could impact a